Heat pump for a vehicle

ABSTRACT

A heat pump includes a refrigerant loop. The refrigerant loop includes a first heat exchanger, a first region of a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a compressor, a vapor generator, and a four-way valve. The compressor includes a low-pressure inlet, a mid-pressure inlet, and an outlet. The vapor generator is positioned downstream of the outlet of the compressor and upstream of both the low-pressure inlet and the mid-pressure inlet. The four-way valve is positioned immediately upstream of the first heat exchanger. At least one component chosen from the first heat exchanger, the second heat exchanger, and the vapor generator is free from compressor-driven flow of the first heat exchange fluid during a first predetermined set of heating modes of operation of the heat pump and a first predetermined set of cooling modes of operation of the heat pump.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to a heat pump. Morespecifically, the present disclosure relates to a heat pump for avehicle.

BACKGROUND OF THE INVENTION

Heat pumps have been employed in vehicles. A refrigerant loop can beincluded in such heat pumps.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, a heat pumpincludes a refrigerant loop. The refrigerant loop includes a first heatexchanger, a first region of a second heat exchanger, a third heatexchanger, a fourth heat exchanger, a compressor, a vapor generator, anda four-way valve. The compressor includes a low-pressure inlet, amid-pressure inlet, and an outlet. The vapor generator is positioneddownstream of the outlet of the compressor and upstream of both thelow-pressure inlet and the mid-pressure inlet. The four-way valve ispositioned immediately upstream of the first heat exchanger. At leastone component chosen from the first heat exchanger, the second heatexchanger, and the vapor generator is free from compressor-driven flowof the first heat exchange fluid during a first predetermined set ofheating modes of operation of the heat pump and a first predeterminedset of cooling modes of operation of the heat pump.

Embodiments of the first aspect of the invention can include any one ora combination of the following features:

-   -   the refrigerant loop further includes a first three-way valve        positioned downstream of the outlet of the compressor and        upstream of an inlet of the first heat exchanger, wherein the        first three-way valve is positioned upstream of the first region        of the second heat exchanger;    -   the four-way valve is positioned downstream of the first        three-way valve;    -   the refrigerant loop further includes a second three-way valve        positioned immediately downstream of the first heat exchanger;    -   the refrigerant loop further includes a third three-way valve        positioned downstream of the third heat exchanger, wherein the        third three-way valve is positioned downstream of the fourth        heat exchanger, and wherein the third three-way valve is        positioned upstream of the low-pressure inlet;    -   the refrigerant loop further includes an accumulator positioned        immediately upstream of the low-pressure inlet of the compressor        and immediately downstream of the third three-way valve;    -   the refrigerant loop further includes a first shutoff valve        plumbed in series with the first heat exchanger and a second        shutoff valve plumbed in series with the first heat exchanger,        wherein the first shutoff valve is in a closed position when the        second shutoff valve is in an open position, and wherein the        second shutoff valve is in a closed position when the first        shutoff valve is in an open position;    -   the refrigerant loop further includes a third shutoff valve        positioned downstream of the vapor generator;    -   the vapor generator is a liquid-gas separator valve;    -   the vapor generator is a plate-style heat exchanger;    -   the refrigerant loop further includes a first expansion valve        positioned upstream of a first region of the vapor generator;    -   the refrigerant loop further includes a second expansion valve        positioned upstream of the four-way valve, a third expansion        valve positioned immediately upstream of the third heat        exchanger, and a fourth expansion valve positioned immediately        upstream of the fourth heat exchanger; and    -   a coolant loop that includes a second region of the second heat        exchanger, a pump, a fifth heat exchanger, a reservoir, and a        coolant network of conduits that fluidly couples components of        the coolant loop.

According to a second aspect of the present disclosure, a heat pumpincludes a refrigerant loop. The refrigerant loop includes a refrigerantnetwork of conduits that fluidly couples components of the refrigerantloop and a first heat exchange fluid that circulates through therefrigerant network of conduits. The refrigerant loop also includes acompressor having a low-pressure inlet, a mid-pressure inlet, and anoutlet. The refrigerant loop further includes a first heat exchanger, afirst region of a second heat exchanger, a third heat exchanger, afourth heat exchanger, a vapor generator, a first three-way valve, and afour-way valve. The vapor generator is positioned downstream of theoutlet of the compressor and upstream of both the low-pressure inlet andthe mid-pressure inlet. The first three-way valve is positioneddownstream of the outlet of the compressor and upstream of an inlet ofthe first heat exchanger. The first three-way valve is positionedupstream of the first region of the second heat exchanger. The four-wayvalve is positioned immediately upstream of the first heat exchanger.The four-way valve is positioned downstream of the first three-wayvalve. At least one component chosen from the first heat exchanger, thesecond heat exchanger, and the vapor generator is free fromcompressor-driven flow of the first heat exchange fluid during a firstpredetermined set of heating modes of operation of the heat pump and afirst predetermined set of cooling modes of operation of the heat pump.

Embodiments of the second aspect of the present disclosure can includeany one or a combination of the following features:

-   -   the refrigerant loop further includes a second three-way valve        positioned immediately downstream of the first heat exchanger;    -   the refrigerant loop further includes a third three-way valve        positioned downstream of the third heat exchanger, wherein the        third three-way valve is positioned downstream of the fourth        heat exchanger, and wherein the third three-way valve is        positioned upstream of the low-pressure inlet;    -   the refrigerant loop further includes a first shutoff valve        plumbed in series with the first heat exchanger, a second        shutoff valve plumbed in series with the first heat exchanger,        wherein the first shutoff valve is in a closed position when the        second shutoff valve is in an open position, and wherein the        second shutoff valve is in a closed position when the first        shutoff valve is in an open position, and a third shutoff valve        is positioned downstream of the vapor generator;    -   the refrigerant loop further includes a first expansion valve        positioned upstream of a first region of the vapor generator, a        second expansion valve positioned upstream of the four-way        valve, a third expansion valve positioned immediately upstream        of the third heat exchanger, and a fourth expansion valve        positioned immediately upstream of the fourth heat exchanger;    -   the refrigerant loop further includes an accumulator positioned        immediately upstream of the low-pressure inlet of the compressor        and immediately downstream of the third three-way valve; and    -   a coolant loop that includes a second region of the second heat        exchanger, a pump, a fifth heat exchanger, a reservoir, and a        coolant network of conduits that fluidly couples components of        the coolant loop.

These and other aspects, objects, and features of the present disclosurewill be understood and appreciated by those skilled in the art uponstudying the following specification, claims, and appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a schematic representation of a heat pump arrangement,illustrating a refrigerant loop and a coolant loop, according to oneexample;

FIG. 2 is a schematic representation of the heat pump arrangement,illustrating a cabin cooling mode of operation, according to oneexample;

FIG. 3 is a schematic representation of the heat pump arrangement,illustrating a cabin and battery cooling mode of operation, according toone example;

FIG. 4 is a schematic representation of the heat pump arrangement,illustrating a battery cooling mode of operation, according to oneexample;

FIG. 5 is a schematic representation of the heat pump arrangement,illustrating a heating mode of operation, according to one example;

FIG. 6 is a schematic representation of the heat pump arrangement,illustrating a first reheat mode of operation, according to one example;

FIG. 7 is a schematic representation of the heat pump arrangement,illustrating a second reheat mode of operation, according to oneexample;

FIG. 8 is a schematic representation of the heat pump arrangement,illustrating a third reheat mode of operation, according to one example;

FIG. 9 is a schematic representation of the heat pump arrangement,illustrating a fourth reheat mode of operation, according to oneexample;

FIG. 10 is a schematic representation of the heat pump arrangement,illustrating a first deicing mode of operation, according to oneexample;

FIG. 11 is a schematic representation of the heat pump arrangement,illustrating a second deicing mode of operation, according to oneexample; and

FIG. 12 is a schematic representation of the heat pump arrangement,illustrating a heating and deicing mode of operation, according to oneexample.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

For purposes of description herein, the terms “upper,” “lower,” “right,”“left,” “rear,” “front,” “vertical,” “horizontal,” and derivativesthereof shall relate to the concepts as oriented in FIG. 1 . However, itis to be understood that the concepts may assume various alternativeorientations, except where expressly specified to the contrary. It isalso to be understood that the specific devices and processesillustrated in the attached drawings, and described in the followingspecification are simply exemplary embodiments of the inventive conceptsdefined in the appended claims. Hence, specific dimensions and otherphysical characteristics relating to the embodiments disclosed hereinare not to be considered as limiting, unless the claims expressly stateotherwise.

The present illustrated embodiments reside primarily in combinations ofmethod steps and apparatus components related to a heat pump.Accordingly, the apparatus components and method steps have beenrepresented, where appropriate, by conventional symbols in the drawings,showing only those specific details that are pertinent to understandingthe embodiments of the present disclosure so as not to obscure thedisclosure with details that will be readily apparent to those ofordinary skill in the art having the benefit of the description herein.Further, like numerals in the description and drawings represent likeelements.

As used herein, the term “and/or,” when used in a list of two or moreitems, means that any one of the listed items can be employed by itself,or any combination of two or more of the listed items, can be employed.For example, if a composition is described as containing components A,B, and/or C, the composition can contain A alone; B alone; C alone; Aand B in combination; A and C in combination; B and C in combination; orA, B, and C in combination.

In this document, relational terms, such as first and second, top andbottom, and the like, are used solely to distinguish one entity oraction from another entity or action, without necessarily requiring orimplying any actual such relationship or order between such entities oractions. The terms “comprises,” “comprising,” or any other variationthereof, are intended to cover a non-exclusive inclusion, such that aprocess, method, article, or apparatus that comprises a list of elementsdoes not include only those elements but may include other elements notexpressly listed or inherent to such process, method, article, orapparatus. An element proceeded by “comprises . . . a” does not, withoutmore constraints, preclude the existence of additional identicalelements in the process, method, article, or apparatus that comprisesthe element.

As used herein, the term “about” means that amounts, sizes,formulations, parameters, and other quantities and characteristics arenot and need not be exact, but may be approximate and/or larger orsmaller, as desired, reflecting tolerances, conversion factors, roundingoff, measurement error and the like, and other factors known to those ofskill in the art. When the term “about” is used in describing a value oran end-point of a range, the disclosure should be understood to includethe specific value or end-point referred to. Whether or not a numericalvalue or end-point of a range in the specification recites “about,” thenumerical value or end-point of a range is intended to include twoembodiments: one modified by “about,” and one not modified by “about.”It will be further understood that the end-points of each of the rangesare significant both in relation to the other end-point, andindependently of the other end-point.

The terms “substantial,” “substantially,” and variations thereof as usedherein are intended to note that a described feature is equal orapproximately equal to a value or description. For example, a“substantially planar” surface is intended to denote a surface that isplanar or approximately planar. Moreover, “substantially” is intended todenote that two values are equal or approximately equal. In someembodiments, “substantially” may denote values within about 10% of eachother, such as within about 5% of each other, or within about 2% of eachother.

As used herein the terms “the,” “a,” or “an,” mean “at least one,” andshould not be limited to “only one” unless explicitly indicated to thecontrary. Thus, for example, reference to “a component” includesembodiments having two or more such components unless the contextclearly indicates otherwise.

Referring to FIGS. 1-12 , reference numeral 20 generally designates aheat pump. The heat pump 20 includes a refrigerant loop 24. Therefrigerant loop 24 includes a first heat exchanger 28, a second heatexchanger 32, a third heat exchanger 36, a fourth heat exchanger 40, acompressor 44, a vapor generator 48, and a four-way valve 52. Thecompressor 44 includes a low-pressure inlet 56, a mid-pressure inlet 60,and an outlet 64. The vapor generator 48 is positioned downstream of theoutlet 64 of the compressor 44 and upstream of both the low-pressureinlet 56 and the mid-pressure inlet 60. The four-way valve 52 ispositioned immediately upstream of the first heat exchanger 28. Arefrigerant network of conduits 68 fluidly couples the variouscomponents of the refrigerant loop 24. A first heat exchange fluid iscirculated through the refrigerant network of conduits 68. Therefrigerant network of conduits 68 is fluidly coupled with variouscomponents of the refrigerant loop 24 that will be discussed herein. Forthe sake of brevity and clarity, individual sections of the refrigerantnetwork of conduits 68 will not be discussed unless additional clarityis provided by such discussion. Rather, the flow of the first heatexchange fluid will be described with regard to the interaction betweenthe first heat exchange fluid and the various components of therefrigerant loop 24. At least one component chosen from the first heatexchanger 28, the second heat exchanger 32, and the vapor generator 48is free from flow driven by the compressor 44 (i.e., compressor-drivenflow) of the first heat exchange fluid during a first predetermined setof heating modes of operation of the heat pump 20 and a firstpredetermined set of cooling modes of operation of the heat pump 20, aswill be discussed in further detail herein.

Referring again to FIGS. 1-12 , the refrigerant loop 24 of the heat pump20 also includes a first three-way valve 72 that is positioneddownstream of the outlet 64 of the compressor 44. The first three-wayvalve 72 is positioned upstream of an inlet 76 of the first heatexchanger 28. The first three-way valve 72 is also positioned upstreamof a first region 80 of the second heat exchanger 32. The four-way valve52 is positioned downstream of the first three-way valve 72. A secondthree-way valve 84 is positioned immediately downstream of the firstheat exchanger 28. A third three-way valve 88 is positioned downstreamof the third heat exchanger 36. The third three-way valve 88 is alsopositioned downstream of the fourth heat exchanger 40. The thirdthree-way valve 88 is positioned upstream of the low-pressure inlet 56of the compressor 44. In various examples, an accumulator 92 can bepositioned immediately upstream of the low-pressure inlet 56 of thecompressor 44 and immediately downstream of the third three-way valve88. The accumulator 92 may be a suction accumulator. In general, theaccumulator 92 can protect the compressor 44 from liquid slugging orliquid being introduced into the compressor 44. The accumulator 92 canalso retain moisture and contaminants from the refrigerant loop 24 andensure that only refrigerant, such as the first heat exchange fluid, isreturning to the compressor 44. It is contemplated that a receiver-dryermay be used in place of the accumulator 92 or in addition to theaccumulator 92. In examples that employ the receiver-dryer, thereceiver-dryer can be positioned along the refrigerant loop 24 (e.g.,along the refrigerant network of conduits 68). When employed, thereceiver-dryer can act as a temporary storage container for the firstheat exchange fluid during low system demands when operating the heatpump 20. Additionally, the receiver-dryer can contain a desiccant thatis used to absorb moisture (e.g., water) that may have entered the firstheat exchange fluid. In some examples, the receiver-dryer may include afilter that can trap debris that may have entered into the refrigerantloop 24 and/or the first heat exchange fluid.

Referring further to FIGS. 1-12 , the refrigerant loop 24 can include afirst shutoff valve 96 that is plumbed in series with the first heatexchanger 28. Additionally, the refrigerant loop 24 includes a secondshutoff valve 100 that is plumbed in series with the first heatexchanger 28. In various examples, the first shutoff valve 96 may beplaced in a closed position when the second shutoff valve 100 is in anopen position. Similarly, the second shutoff valve 100 may be placed ina closed position when the first shutoff valve 96 is in an openposition. In some examples of the heat pump 20, the first shutoff valve96 and the second shutoff valve 100 may be opened in a mutuallyexclusive manner That is to say, in some examples, that the compressor44 may drive the first heat exchange fluid through only one of the firstshutoff valve 96 or the second shutoff valve 100 during the operation ofa given mode of operation of the heat pump 20, as will be discussed infurther detail herein. A third shutoff valve 104 can be positioneddownstream of the vapor generator 48. In various examples, the vaporgenerator 48 can be a liquid-gas separator valve. In such examples, theliquid-gas separator valve may perform a thermal phase separation and/ora mechanical phase separation, whereby a gaseous component of the firstheat exchange fluid that is circulating through the refrigerant loop 24is extracted, at least in part. The portion of the gaseous component ofthe first heat exchange fluid extracted by the liquid-gas separatorvalve may then be injected into the compressor at the mid-pressure inlet60. Additionally, in such examples, the remainder of the first heatexchange fluid, which may contain liquid and gas components, iscirculated through the refrigerant network of conduits 68 to remainingcomponents of the refrigerant loop 24 for the given mode of operation.This remaining portion of the first heat exchange fluid eventually isdirected to the low-pressure inlet 56 of the compressor 44. Inalternative examples, the vapor generator 48 may be a plate-style heatexchanger. In such examples, the vapor generator 48 includes a firstregion 108 and a second region 112.

Referring still further to FIGS. 1-12 , a first expansion valve 116 ispositioned upstream of the first region 108 of the vapor generator 48. Asecond expansion valve 120 is positioned upstream of the four-way valve52. A third expansion valve 124 is positioned immediately upstream ofthe third heat exchanger 36. A fourth expansion valve 128 is positionedimmediately upstream of the fourth heat exchanger 40. The heat pump 20can further include a coolant loop 132. The coolant loop 132 includes apump 136, a second region 140 of the second heat exchanger 32, areservoir 144, a fifth heat exchanger 148, and a coolant network ofconduits 152 that fluidly couples components of the coolant loop 132. Asecond heat exchange fluid flows through the coolant network of conduits152 of the coolant loop 132, as well as the components of the coolantloop 132. The first and second heat exchange fluids thermally interactby way of the second heat exchanger 32. More specifically, as the firstand second heat exchange fluids flow through the first region 80 and thesecond region 140 of the second heat exchanger 32, respectively, thefirst and second heat exchange fluids thermally interact. In variousexamples, the fifth heat exchanger 148 can be in fluid communicationwith ductwork 154 of a Heating, Ventilation, and Air Conditioning (HVAC)system. Similarly, the third heat exchanger 36 can be in fluidcommunication with the ductwork 154 of the HVAC system. Accordingly, thethird and fifth heat exchangers 36, 148 may be employed to alter atemperature of ambient air and provide temperature-controlled air to anenvironment (e.g., a cabin of a vehicle).

Referring now to FIGS. 2-4 , exemplary modes of operation are depicted.More specifically, a cabin cooling mode of operation (FIG. 2 ), a cabinand battery cooling mode of operation (FIG. 3 ), and a battery coolingmode of operation (FIG. 4 ) are depicted in exemplary fatal. In each ofthese modes of operation, the four-way valve 52 includes a first port156, a second port 160, a third port 164, and a fourth port 168. Anexpanded view of the four-way valve 52 is inset into FIGS. 2-4 to aid indiscussion of the operation of the four-way valve 52 in the given modeof operation. In each of these modes of operation, the coolant loop 132may be omitted from use. For example, the pump 136 that is positionedwithin the coolant loop 132 may be placed in an off state. Said anotherway, in each of these modes of operation, the first region 80 of thesecond heat exchanger 32 does not receive flow of the first heatexchange fluid that is driven by the compressor 44. In the cabin coolingmode of operation (FIG. 2 ), the fourth heat exchanger 40 and the fourthexpansion valve 128 may be omitted from flow of the first heat exchangefluid, as driven by the compressor 44. Similarly, in the battery coolingmode of operation (FIG. 4 ), the third heat exchanger 36 and the thirdexpansion valve 124 may be omitted from flow of the first heat exchangefluid, as driven by the compressor 44. For example, the third expansionvalve 124 may be capable of operating as a shutoff valve such that thethird expansion valve 124 is placed in a closed state that prevents flowof the first heat exchange fluid from passing through the third heatexchanger 36. Similarly, the fourth expansion valve 128 may be capableof operating as a shutoff valve such that the fourth expansion valve 128is placed in a closed state that prevents flow of the first heatexchange fluid from passing through the fourth heat exchanger 40.

Referring again to FIGS. 2-4 , the position of the first three-way valve72 may prevent the first heat exchange fluid from interacting with thesecond heat exchanger 32. The compressor 44 acts upon the first heatexchange fluid and drives the first heat exchange fluid from the outlet64 toward the first three-way valve 72. The first heat exchange fluidenters a first port 172 of the first three-way valve 72 and exits asecond port 176 of the first three-way valve 72 as a result of theposition of the first three-way valve 72. After exiting the second port176 of the first three-way valve 72, the first heat exchange fluid flowsto the first port 156 of the four-way valve 52. The four-way valve 52 isadjusted in its position to receive the first heat exchange fluid at thefirst port 156 such that the first port 156 operates as an inlet, asindicated by arrow 180. The position of the four-way valve 52 directsthe first heat exchange fluid received at the first port 156 to exit thefour-way valve 52 at the fourth port 168, as indicated by arrow 184.Upon exiting the fourth port 168 of the four-way valve 52, the firstheat exchange fluid enters the first heat exchanger 28 at the inlet 76of the first heat exchanger 28. As the first heat exchange fluid flowsthrough the first heat exchanger 28, the first heat exchange fluid maythermally interact with a heat exchange fluid that is external to therefrigerant loop 24 and the coolant loop 132 (e.g., ambient air) suchthat heat may be removed from the first heat exchange fluid. The firstheat exchange fluid exits the first heat exchanger 28 at an outlet 188of the first heat exchanger 28. Upon exiting the first heat exchanger 28by way of the outlet 188, the first heat exchange fluid enters into afirst port 192 of the second three-way valve 84. The second three-wayvalve 84 is positioned such that the first heat exchange fluid isdirected to a second port 196 of the second three-way valve 84. In eachof these modes of operation, the second shutoff valve 100 is in theclosed position and the first shutoff valve 96 is in the open position.Upon exiting the second port 196 of the second three-way valve 84, thefirst heat exchange fluid is directed toward the first shutoff valve 96by the refrigerant network of conduits 68.

Referring further to FIGS. 2-4 , after flowing through the first shutoffvalve 96, the first heat exchange fluid encounters a first couplingpoint 200 between sections of the refrigerant network of conduits 68.From the first coupling point 200, the first heat exchange fluid isdirected toward a first branching point 204. As the first heat exchangefluid encounters the first branching point 204, a portion of the firstheat exchange fluid is diverted toward the first expansion valve 116,while the remaining portion of the first heat exchange fluid continuestoward the second region 112 of the vapor generator 48. In variousexamples, the portion of the first heat exchange fluid that is divertedtoward the first expansion valve 116 can be expressed as a ratio orpercentage. For example, expressing the ratio as a percentage of thefirst heat exchange fluid that is diverted toward the first expansionvalve 116, the first expansion valve 116 can receive about 5%, about10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%,about 45%, about 50%, about 55%, or about 60% of the first heat exchangefluid that encounters the first branching point 204. The remainder, orbalancing percentage, of the first heat exchange fluid that encountersthe first branching point 204 and is not diverted toward the firstexpansion valve 116 can continue toward the second region 112 of thevapor generator 48. It is contemplated that in different modes ofoperation of the heat pump 20, the percentage of the first heat exchangefluid that is received by the first expansion valve 116 may vary. Theportion of the first heat exchange fluid that is diverted toward thefirst expansion valve 116 flows through the first expansion valve 116and is directed toward an inlet 208 of the first region 108 of the vaporgenerator 48. This diverted portion of the first heat exchange fluidflows through the first region 108 and exits the vapor generator 48 atan outlet 212 of the vapor generator 48. The portion of the first heatexchange fluid that was diverted toward the first expansion valve 116decreases in pressure and temperature as a result of interaction withthe first expansion valve 116. Accordingly, the first heat exchangefluid flowing through the first region 108 of the vapor generator 48 hasa lower pressure and temperature than the first heat exchange fluidflowing through the second region 112. Therefore, the first heatexchange fluid within the first region 108 thermally interacts with thefirst heat exchange fluid flowing through the second region 112 of thevapor generator 48.

Referring still further to FIGS. 2-4 , as a result of the thermalinteraction between the first heat exchange fluid within the firstregion 108 and the first heat exchange fluid within the second region112, the first heat exchange fluid within the first region 108 exits thevapor generator 48 at the outlet 212 of the first region 108 at a highertemperature, pressure, and/or vapor percentage than the first heatexchange fluid that entered the inlet 208 of the first region 108. Thefirst heat exchange fluid that exits the first region 108 by way of theoutlet 212 is directed toward the mid-pressure inlet 60 of thecompressor 44, The first heat exchange fluid from the first region 108of the vapor generator 48 is injected into the compressor 44. Theinjection of the first heat exchange fluid at the mid-pressure inlet 60of the compressor 44 can improve efficiency of the refrigerant loop 24and/or increase a heat exchange capacity of the refrigerant loop 24. Forexample, the injection the first heat exchange fluid at the mid-pressureinlet 60 of the compressor 44 can increase a condensing capacity of therefrigerant loop 24 while decreasing a load experienced by thecompressor 44. The improved condensing capacity of the refrigerant loop24 and the decreased load on the compressor 44 can contribute toperformance and efficiency improvements for the heat pump 20 and/or therefrigerant loop 24. Additionally, the injection of the first heatexchange fluid at the mid-pressure inlet 60 can increase an ambienttemperature operating range of the heat pump 20 and/or the refrigerantloop 24.

Referring yet again to FIGS. 2-4 , the portion of the first heatexchange fluid that was not diverted toward the first expansion valve116 and instead flowed toward an inlet 216 of the second region 112 ofthe vapor generator 48 thermally interacts with the first heat exchangefluid that was diverted toward the first expansion valve 116. Duringthis thermal interaction between the first heat exchange fluid withinthe second region 112 and the first exchange fluid within the firstregion 108, heat is transferred from the first heat exchange fluidwithin the second region 112 to the first heat exchange fluid within thefirst region 108. Accordingly, the first heat exchange fluid exiting thevapor generator 48 at an outlet 220 of the second region 112 may be at adifferent temperature, pressure, and/or vapor percentage than the firstheat exchange fluid that entered the inlet 216. For example, the firstheat exchange fluid that exits the vapor generator 48 at the outlet 220of the second region 112 may have a lower temperature and pressure thanwhen the first heat exchange fluid entered the inlet 216 of the secondregion 112. Upon exiting the outlet 220 of the second region 112, thefirst heat exchange fluid is directed toward the third shutoff valve104. The first heat exchange fluid flows through the third shutoff valve104 as a result of the third shutoff valve 104 being in the openposition.

With specific reference to FIG. 2 , from the third shutoff valve 104,the first heat exchange fluid is directed toward the third expansionvalve 124 by the refrigerant network of conduits 68. As with the firstexpansion valve 116, the first heat exchange fluid experiences adecrease in pressure and temperature as a result of interaction with thethird expansion valve 124. After exiting the third expansion valve 124,the first heat exchange fluid is directed toward an inlet 224 of thethird heat exchanger 36. The decreased temperature and pressure of thefirst heat exchange fluid flowing through the third heat exchanger 36can be employed to provide cooling to air that is flowing through theductwork 154 with which the third heat exchanger 36 is in fluidcommunication. Accordingly, the first heat exchange fluid that exits thethird heat exchanger 36 by way of an outlet 228 of the third heatexchanger 36 may have an increased pressure, temperature, and/or vaporpercentage than the first heat exchange fluid that entered the thirdheat exchanger 36 at the inlet 224. Upon exiting the third heatexchanger 36 by way of the outlet 228, the first heat exchange fluid isdirected toward a first port 232 of the third three-way valve 88. As aresult of the position of the third three-way valve 88, the first heatexchange fluid that is received at the first port 232 is directed out ofa second port 236 of the third three-way valve and toward theaccumulator 92. The accumulator 92 receives the first heat exchangefluid and provides a gaseous component of the first heat exchange fluidto the low-pressure inlet 56 of the compressor 44, thereby completingthe traversal of the refrigerant loop 24 in the cabin cooling mode ofoperation.

With specific reference to FIG. 3 , the cabin and battery cooling modeof operation is depicted according to one example. From the thirdshutoff valve 104, the first heat exchange fluid is directed toward thethird expansion valve 124 by the refrigerant network of conduits 68. Onthe way to the third expansion valve 124, the first heat exchange fluidencounters a second branching point 240. At the second branching point240, a first portion of the first heat exchange fluid is directed towardthe fourth expansion valve 128 and a second portion of the first heatexchange fluid is directed toward the third expansion valve 124. Thefirst portion of the first heat exchange fluid experiences a decrease inpressure and temperature as a result of interaction with the fourthexpansion valve 128, Similarly, the second portion of the first heatexchange fluid experiences a decrease in pressure and temperature as aresult of the interaction with the third expansion valve 124. Afterexiting the third expansion valve 124, the first heat exchange fluid isdirected toward the inlet 224 of the third heat exchanger 36. Thedecreased temperature and pressure of the first heat exchange fluidflowing through the third heat exchanger 36 can be employed to providecooling to air that is flowing through the ductwork 154 with which thethird heat exchanger 36 is in fluid communication. Accordingly, thefirst heat exchange fluid that exits the third heat exchanger 36 by wayof the outlet 228 of the third heat exchanger 36 may have an increasedpressure, temperature, and/or vapor percentage than the first heatexchange fluid that entered the third heat exchanger 36 at the inlet224.

Referring again to FIG. 3 , upon exiting the third heat exchanger 36 byway of the outlet 228, the first heat exchange fluid is directed towardthe first port 232 of the third three-way valve 88. Similarly, afterexiting the fourth expansion valve 128, the first heat exchange fluid isdirected toward an inlet 244 of the fourth heat exchanger 40. Thedecreased temperature and pressure of the first heat exchange fluidflowing through the fourth heat exchanger 40 as a result of interactionwith the fourth expansion valve 128 can be employed to decrease thetemperature of heat-producing components with which the fourth heatexchanger 40 interacts (e.g., electric motors, batteries, electronics,etc.). Accordingly, the first heat exchange fluid that exits the fourthheat exchanger 40 by way of an outlet 248 of the fourth heat exchanger40 may have an increased pressure, temperature, and/or vapor percentagethan the first heat exchange fluid that entered the fourth heatexchanger 40 at the inlet 244. Upon exiting the fourth heat exchanger 40by way of the outlet 248, the first heat exchange fluid is directedtoward a check valve 252 by the refrigerant network of conduits 68. Inmodes of operation where the first heat exchange fluid does not passthrough the check valve 252 but the first heat exchange fluid does passthrough the third heat exchanger 36 (e.g., FIGS. 2, 6, and 8 ), thecheck valve 252 prevents back flow toward the fourth heat exchanger 40.Accordingly, the check valve 252 prevents the fourth heat exchanger 40from becoming a storage vessel for the first heat exchange fluid whenthe fourth heat exchanger 40 is not employed in a given mode ofoperation.

Referring further to FIG. 3 , once the first heat exchange fluid passesthrough the check valve 252, the first portion of the first heatexchange fluid that was directed toward the fourth heat exchanger 40 isrejoined or recombined with the second portion of the first heatexchange fluid that was directed toward the third heat exchanger 36. Thefirst and second portions of the first heat exchange fluid are rejoinedor recombined downstream of the outlet 228 of the third heat exchanger36. The check valve 252 prevents backflow or excessive back pressure atthe outlet 248 of the fourth heat exchanger 40. From the check valve252, the first heat exchange fluid is directed toward the first port 232of the third three-way valve 88. As a result of the position of thethird three-way valve 88, the first heat exchange fluid that is receivedat the first port 232 is directed out of the second port 236 of thethird three-way valve and toward the accumulator 92. The accumulator 92receives the first heat exchange fluid and provides a gaseous componentof the first heat exchange fluid to the low-pressure inlet 56 of thecompressor 44.

Referring particularly to FIG. 4 , the battery cooling mode of operationis depicted in exemplary form. The fourth heat exchanger 40 can beassociated with a battery pack of the vehicle or another component ofthe vehicle that produces heat, where the operation of such anothercomponent may benefit from the removal or dispersal of the heatproduced. During the battery cooling mode of operation, the coolant loop132 may be omitted from operation. The first heat exchange fluid iscirculated through the fourth heat exchanger 40 but not through thethird heat exchanger 36. From the third shutoff valve 104, the firstheat exchange fluid is directed toward the third expansion valve 124 bythe refrigerant network of conduits 68. On the way to the third shutoffvalve 104, the first heat exchange fluid encounters the second branchingpoint 240. The first heat exchange fluid is entirely diverted toward thefourth expansion valve 128 at the second branching point 240 without anyappreciable amount of the first heat exchange fluid being directedtoward the third expansion valve 124 or the fourth heat exchanger 40.Preventing the first heat exchange fluid from being directed toward thethird expansion valve 124 and the third heat exchanger 36 may beaccomplished, for example, by supplying a shutoff valve between thesecond branching point 240 and the third expansion valve 124 or by thethird expansion valve 124 being capable of additionally operating as ashutoff valve. Regardless of the particular approach used to prevent thefirst heat exchange fluid from interacting with the third expansionvalve 124 and the third heat exchanger 36, the first heat exchange fluidis directed entirely toward the fourth expansion valve 128. The firstheat exchange fluid experiences a decrease in pressure and temperatureas a result of interaction with the fourth expansion valve 128.

Referring again to FIG. 4 , after exiting the fourth expansion valve128, the first heat exchange fluid is directed toward the inlet 244 ofthe fourth heat exchanger 40. The decreased temperature and pressure ofthe first heat exchange fluid flowing through the fourth heat exchanger40 can be employed to decrease the temperature of heat-producingcomponents with which the fourth heat exchanger 40 interacts (e.g.,electric motors, batteries, electronics, etc.). Accordingly, the firstheat exchange fluid that exits the fourth heat exchanger 40 by way ofthe outlet 248 of the fourth heat exchanger 40 may have an increasedpressure, temperature, and/or vapor percentage than the first heatexchange fluid that entered the fourth heat exchanger 40 at the inlet244. Upon exiting the fourth heat exchanger 40 by way of the outlet 248,the first heat exchange fluid is directed toward the check valve 252 bythe refrigerant network of conduits 68. Once the first heat exchangefluid passes through the check valve 252, the first heat exchange fluidis directed toward the first port 232 of the third three-way valve 88.For example, the same approach that accomplished the prevention of thefirst heat exchange fluid from progressing to the third expansion valve124 can provide sufficient flow resistance to prevent the first heatexchange fluid from entering the outlet 228 of the third heat exchanger36 after passing through the check valve 252. As a result of theposition of the third three-way valve 88, the first heat exchange fluidthat is received at the first port 232 is directed out of the secondport 236 of the third three-way valve and toward the accumulator 92. Theaccumulator 92 receives the first heat exchange fluid and provides agaseous components of the first heat exchange fluid to the low-pressureinlet 56 of the compressor 44.

Referring now to FIGS. 5-9 , various modes of operation of the heat pump20 that employ the coolant loop 132 are depicted. The pump 136 isactivated in these modes of operation such that a second heat exchangefluid is circulated through the components of the coolant loop 132. Thesecond heat exchange fluid is driven from the pump 136 toward the secondheat exchanger 32. Accordingly, the second heat exchange fluid thermallyinteracts with the first heat exchange fluid by way of the second heatexchanger 32. More specifically, the second heat exchange fluid iscirculated through the second region 140 of the second heat exchanger 32while the first heat exchange fluid is circulated through the firstregion 80 of the second heat exchanger 32. In various examples, thesecond heat exchange fluid may extract heat from the first heat exchangefluid at the second heat exchanger 32. From the second heat exchanger32, the second heat exchange fluid is directed to an inlet 254 of thereservoir 144 by the coolant network of conduits 152. The reservoir 144can accumulate the second heat exchange fluid. An outlet 256 of thereservoir 144 is plumbed to an inlet 260 of the fifth heat exchanger 148by the coolant network of conduits 152. An outlet 264 of the fifth heatexchanger 148 is plumbed to the pump 136. Accordingly, as the pump 136is operated, the second heat exchange fluid is pulled from the reservoir144 and into the inlet 260 of the fifth heat exchanger 148 in asiphon-like manner. Said another way, operation of the pump 136 maygenerate a positive pressure at the inlet 254 of the reservoir 144 and anegative pressure at the outlet 256 of the reservoir. Therefore, thepressure differential across the reservoir 144 can facilitate theintroduction of the second heat exchange fluid into the inlet 260 of thefifth heat exchanger 148. The second heat exchange fluid can provideheat to a cabin of a vehicle as a result of the fluid communicationbetween the fifth heat exchanger 148 and the ductwork 154. For example,the fifth heat exchanger 148 may operate as a heater core.Alternatively, heat from the second heat exchange fluid may betransferred from the fifth heat exchanger 148 to components that canbenefit from such heat, such as batteries or electrical componentsduring cold weather conditions in the environment within which thevehicle or the heat pump 20 currently occupies at a given time.

Referring to FIGS. 5-7 , the compressor 44 acts upon the first heatexchange fluid to drive the first heat exchange fluid from the outlet 64of the compressor 44 toward the first port 172 of the first three-wayvalve 72. The positioning of the first three-way valve 72 in these modesof operation is such that the first heat exchange fluid that is receivedat the first port 172 is directed out of a third port 268 of the firstthree-way valve 72. From the third port 268 of the first three-way valve72, the first heat exchange fluid is directed toward an inlet 272 of thefirst region 80 of the second heat exchanger 32. In each of the depictedexamples, the first shutoff valve 96 is in a closed position such thatas the first heat exchange fluid exits the first region 80 of the secondheat exchanger 32 by way of an outlet 276 of the first region 80, thefirst heat exchange fluid encounters the first coupling point 200 andpasses the first coupling point 200 to continue on to the firstbranching point 204.

Referring again to FIGS. 5-9 , as the first heat exchange fluidencounters the first branching point 204, a portion of the first heatexchange fluid is diverted toward the first expansion valve 116, whilethe remaining portion of the first heat exchange fluid continues towardthe second region 112 of the vapor generator 48, In various examples,the portion of the first heat exchange fluid that is diverted toward thefirst expansion valve 116 can be expressed as a ratio or percentage. Forexample, expressing the ratio as a percentage of the first heat exchangefluid that is diverted toward the first expansion valve 116, the firstexpansion valve 116 can receive about 5%, about 10%, about 15%, about20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%,about 55%, or about 60% of the first heat exchange fluid that encountersthe first branching point 204. The remainder, or balancing percentage,of the first heat exchange fluid that encounters the first branchingpoint 204 and is not diverted toward the first expansion valve 116 cancontinue toward the second region 112 of the vapor generator 48. It iscontemplated that in different modes of operation of the heat pump 20,the percentage of the first heat exchange fluid that is received by thefirst expansion valve 116 may vary.

Referring further to FIGS. 5-9 , the portion of the first heat exchangefluid that is diverted toward the first expansion valve 116 flowsthrough the first expansion valve 116 and is directed toward the inlet208 of the first region 108 of the vapor generator 48. This divertedportion of the first heat exchange fluid flows through the first region108 and exits the vapor generator 48 at the outlet 212 of the firstregion 108 of the vapor generator 48. The portion of the first heatexchange fluid that was diverted toward the first expansion valve 116decreases in pressure and temperature as a result of interaction withthe first expansion valve 116. Accordingly, the first heat exchangefluid flowing through the first region 108 of the vapor generator 48 hasa lower pressure and temperature than the first heat exchange fluidflowing through the second region 112. Therefore, the first heatexchange fluid within the first region 108 thermally interacts with thefirst heat exchange fluid flowing through the second region 112 of thevapor generator 48. As a result of the thermal interaction between thefirst heat exchange fluid within the first region 108 and the first heatexchange fluid within the second region 112, the first heat exchangefluid within the first region 108 exits the vapor generator 48 at theoutlet 212 of the first region 108 at a higher temperature, pressure,and/or vapor percentage than the first heat exchange fluid that enteredthe inlet 208 of the first region 108. The first heat exchange fluidthat exits the first region 108 by way of the outlet 212 is directedtoward the mid-pressure inlet 60 of the compressor 44. The first heatexchange fluid from the first region 108 of the vapor generator 48 isinjected into the compressor 44 in a gaseous state. The injection of thefirst heat exchange fluid at the mid-pressure inlet 60 of the compressor44 can improve efficiency of the refrigerant loop 24 and/or increase aheat exchange capacity of the refrigerant loop 24. For example, theinjection of the first heat exchange fluid at the mid-pressure inlet 60of the compressor 44 can increase a condensing capacity of therefrigerant loop 24 while decreasing a load experienced by thecompressor 44. The improved condensing capacity of the refrigerant loop24 and the decreased load on the compressor 44 can contribute toperformance and efficiency improvements for the heat pump 20 and/or therefrigerant loop 24. Additionally, the injection of the first heatexchange fluid at the mid-pressure inlet 60 can increase an ambienttemperature operating range of the heat pump 20 and/or the refrigerantloop 24.

Referring still further to FIGS. 5-9 , the portion of the first heatexchange fluid that was not diverted toward the first expansion valve116 and instead flowed toward the inlet 216 of the second region 112 ofthe vapor generator 48 thermally interacts with the first heat exchangefluid that was diverted toward the first expansion valve 116. Duringthis thermal interaction between the first heat exchange fluid withinthe second region 112 and the first exchange fluid within the firstregion 108, heat is transferred from the first heat exchange fluidwithin the second region 112 to the first heat exchange fluid within thefirst region 108. Accordingly, the first heat exchange fluid exiting thevapor generator 48 at the outlet 220 of the second region 112 may be ata different temperature, pressure, and/or vapor percentage than thefirst heat exchange fluid that entered the inlet 216. For example, thefirst heat exchange fluid that exits the vapor generator 48 at theoutlet 220 of the second region 112 may have a lower temperature andpressure than when the first heat exchange fluid entered the inlet 216of the second region 112. Upon exiting the outlet 220 of the secondregion 112, the first heat exchange fluid is directed toward the thirdshutoff valve 104. The first heat exchange fluid flows through the thirdshutoff valve 104 as a result of the third shutoff valve 104 being inthe open position.

With specific reference to FIG. 5 , a heating mode of operation isdepicted according to one example. In the heating mode of operation, thefirst heat exchange fluid is directed from the third shutoff valve 104toward the second expansion valve 120. In this mode of operation, thethird expansion valve 124 and the fourth expansion valve 128 prevent thefirst heat exchange fluid from being driven to the third heat exchanger36 and the fourth heat exchanger 40, respectively. Alternatively,shutoff valves may be positioned immediately upstream of the third andfourth expansion valves 124, 128 to accomplish the same end. In eitherinstance, the first heat exchange fluid is directed along therefrigerant network of conduits 68 to interact with the second expansionvalve 120 after leaving the third shutoff valve 104. The first heatexchange fluid experiences a decreases in pressure and temperature as aresult of interaction with the second expansion valve 120. From thesecond expansion valve 120, the first heat exchange fluid is directtoward the third port 164 of the four-way valve 52. Accordingly, thepositioning of the four-way valve 52 in the heating mode of operationemploys the third port 164 of the four-way valve 52 as a first inlet, asindicated by arrow 280. As a result of the positioning of the four-wayvalve 52, the first heat exchange fluid that has entered the third port164 is directed toward the fourth port 168 such that the fourth port 168acts as a first outlet, as indicated by arrow 284. From the fourth port168 of the four-way valve 52, the first heat exchange fluid is directedtoward the inlet 76 of the first heat exchanger 28. Within the firstheat exchanger 28, the first heat exchange fluid may absorb heat fromfluid with which the first heat exchanger 28 is additionally in contact(e.g., ambient air that is exterior to a vehicle).

Referring again to FIG. 5 , upon exiting the first heat exchanger 28 byway of the outlet 188, the first heat exchange fluid is directed towardthe first port 192 of the second three-way valve 84. As a result of thepositioning of the second three-way valve 84 in the heating mode ofoperation, the first heat exchange fluid that has been received at thefirst port 192 is directed toward the second port 196 of the secondthree-way valve 84 such that the second port 196 operates as an outlet.From the second port 196, the first heat exchange fluid is directedtoward the second shutoff valve 100. More specifically, the secondshutoff valve 100 may be positioned along a bridging portion 288 of therefrigerant network of conduits 68. For example, a first end of thebridging portion 288 can be referred to as a first bridging point 292and a second end of the bridging portion 288 can be referred to as asecond bridging point 296. The first bridging point 292 can bepositioned between the second port 196 of the second three-way valve 84and the first shutoff valve 96. The second bridging point 296 can bepositioned between the second port 176 of the first three-way valve 72and the first port 156 of the four-way valve 52. In the heating mode ofoperation, the first shutoff valve 96 is placed in the closed positionand the second shutoff valve 100 is placed in the open position.Accordingly, the first heat exchange fluid that exits the second port196 of the second three-way valve 84 passes through the second shutoffvalve 100 and is directed toward the first port 156 of the four-wayvalve 52, Therefore, the first port 156 of the four-way valve 52operates as a second inlet during the heating mode of operation, asindicated by arrow 300. The first heat exchange fluid that is receivedat the first port 156 is directed out of the second port 160 of thefour-way valve 52 such that the second port 160 operates as a secondoutlet, as indicate by arrow 304. From the second port 160 of thefour-way valve 52, the first heat exchange fluid is directed toward athird port 308 of the third three-way valve 88. The positioning of thethird three-way valve 88 in the heating mode of operation directs thefirst heat exchange fluid received at the third port 308 to exit thethird three-way valve 88 at the second port 236 of the third three-wayvalve 88. From the second port 236 of the third three-way valve 88, thefirst heat exchange fluid is directed toward the accumulator 92, wherethe accumulator 92 performs as outlined previously. The gaseouscomponent of the first heat exchange fluid is then introduced to thelow-pressure inlet 56 of the compressor 44 from the accumulator 92.

Referring now to FIGS. 6 and 7 , from the third shutoff valve 104, thefirst heat exchange fluid is directed toward the third expansion valve124. The second three-way valve 84 is positioned in such a way toprevent the first heat exchange fluid from passing through the secondthree-way valve 84 on its way to the third expansion valve 124. Thefirst heat exchange fluid experiences a decrease in pressure andtemperature as a result of interaction with the third expansion valve124. After exiting the third expansion valve 124, the first heatexchange fluid is directed toward the inlet 224 of the third heatexchanger 36. The decreased temperature and pressure of the first heatexchange fluid flowing through the third heat exchanger 36 can beemployed to provide cooling to air that is flowing through the ductwork154 with which the third heat exchanger 36 is in fluid communication.Accordingly, the first heat exchange fluid that exits the third heatexchanger 36 by way of the outlet 228 of the third heat exchanger 36 mayhave an increased pressure, temperature, and/or vapor percentage thanthe first heat exchange fluid that entered the third heat exchanger 36at the inlet 224. The cooling of the air within the ductwork 154 that isprovided by the third heat exchanger 36 in these modes of operation canbe employed as a way of controlling a humidity level within the aircirculated through the ductwork 154 (e.g., dehumidification). Forexample, the cooling of the air within the ductwork 154 that is providedby the third heat exchanger 36 can result in condensing of at least somegaseous components of the air (e.g., water vapor) passing through theductwork 154. Upon exiting the third heat exchanger 36 by way of theoutlet 228, the first heat exchange fluid is directed toward the firstport 232 of the third three-way valve 88. As a result of the position ofthe third three-way valve 88, the first heat exchange fluid that isreceived at the first port 232 is directed out of the second port 236 ofthe third three-way valve and toward the accumulator 92. The accumulator92 receives the first heat exchange fluid and provides a gaseouscomponent of the first heat exchange fluid to the low-pressure inlet 56of the compressor 44. The mode of operation depicted in FIG. 6 may bereferred to as a first reheat mode of operation. The mode of operationdepicted in FIG. 7 may be referred to as a second reheat mode ofoperation.

With specific reference to FIG. 7 , in addition to the third heatexchanger 36 receiving the first heat exchange fluid that exits thethird shutoff valve 104, the fourth heat exchanger 40 receives the firstheat exchange fluid that has exited the third shutoff valve 104. Morespecifically, in the second reheat mode of operation, the fourthexpansion valve 128 receives a portion of the first heat exchange fluidthat encounters the second branching point 240. As described above, atthe second branching point 240, the first portion of the first heatexchange fluid is directed toward the fourth expansion valve 128 and thesecond portion of the first heat exchange fluid is directed toward thethird expansion valve 124. As the interaction with the third expansionvalve 124 and the third heat exchanger 36 has already been discussedwith regard to the second reheat mode of operation, the interactionbetween the first portion of the first heat exchange fluid, the fourthexpansion valve 128, the fourth heat exchanger 40, and the check valve252 will now be focused on. The first portion of the first heat exchangefluid experiences a decrease in pressure and temperature as a result ofinteraction with the fourth expansion valve 128.

Referring again to FIG. 7 , after exiting the fourth expansion valve128, the first heat exchange fluid is directed toward the inlet 244 ofthe fourth heat exchanger 40. The decreased temperature and pressure ofthe first heat exchange fluid flowing through the fourth heat exchanger40 as a result of interaction with the fourth expansion valve 128 can beemployed to decrease the temperature of heat-producing components withwhich the fourth heat exchanger 40 interacts (e.g., electric motors,batteries, electronics, etc.). Accordingly, the first heat exchangefluid that exits the fourth heat exchanger 40 by way of the outlet 248of the fourth heat exchanger 40 may have an increased pressure,temperature, and/or vapor percentage than the first heat exchange fluidthat entered the fourth heat exchanger 40 at the inlet 244. Upon exitingthe fourth heat exchanger 40 by way of the outlet 248, the first heatexchange fluid is directed toward the check valve 252 by the refrigerantnetwork of conduits 68. Once the first heat exchange fluid passesthrough the check valve 252, the first portion of the first heatexchange fluid that was directed toward the fourth heat exchanger 40 isrejoined or recombined with the second portion of the first heatexchange fluid that was directed toward the third heat exchanger 36. Thefirst and second portions of the first heat exchange fluid are rejoinedor recombined downstream of the outlet 228 of the third heat exchanger36. The check valve 252 prevents backflow or excessive back pressure atthe outlet 248 of the fourth heat exchanger 40. From the check valve252, the first heat exchange fluid is directed toward the first port 232of the third three-way valve 88. As a result of the position of thethird three-way valve 88, the first heat exchange fluid that is receivedat the first port 232 is directed out of the second port 236 of thethird three-way valve and toward the accumulator 92. The accumulator 92receives the first heat exchange fluid and provides a gaseous componentsof the first heat exchange fluid to the low-pressure inlet 56 of thecompressor 44.

Referring now to FIGS. 8 and 9 , a third reheat mode of operation (FIG.8 ) and a fourth reheat mode of operation (FIG. 9 ) are depicted inexemplary form. The third reheat mode of operation may additionally, oralternatively, be referred to as a first defrost mode of operation.Similarly, the fourth reheat mode of operation may additionally, oralternatively, be referred to as a second defrost mode of operation. Inthese modes of operation, the first three-way valve 72 is positionedsuch that the first heat exchange fluid received from the outlet 64 ofthe compressor 44 by the first port 172 of the first three-way valve 72is directed to exit the second port 176 and the third port 268. Invarious examples, the first three-way valve 72 may be a three-wayproportional valve that includes one inlet and two outlets.Alternatively, in some examples, the first three-way valve 72 may besubstituted for two two-way valves to accomplish the fluidic controlarticulated herein. The portion of the first heat exchange fluid thatexits the first three-way valve 72 by way of the second port 176 flowsto the first port 156 of the four-way valve 52. The four-way valve 52 isadjusted in its position to receive the first heat exchange fluid at thefirst port 156 such that the first port 156 operates as an inlet, asindicated by arrow 312. The position of the four-way valve 52 directsthe first heat exchange fluid received at the first port 156 to exit thefour-way valve 52 at the fourth port 168, as indicated by arrow 316.Upon exiting the fourth port 168 of the four-way valve 52, the firstheat exchange fluid enters the first heat exchanger 28 at the inlet 76of the first heat exchanger 28. As the first heat exchange fluid flowsthrough the first heat exchanger 28, the first heat exchange fluid maythermally interact with a heat exchange fluid that is external to therefrigerant loop 24 and the coolant loop 132 (e.g., ambient air) suchthat heat may be removed from the first heat exchange fluid.

Referring again to FIGS. 8 and 9 , the first heat exchange fluid exitsthe first heat exchanger 28 at the outlet 188 of the first heatexchanger 28. Upon exiting the first heat exchanger 28 by way of theoutlet 188, the first heat exchange fluid enters into the first port 192of the second three-way valve 84. The second three-way valve 84 ispositioned such that the first heat exchange fluid is directed to thesecond port 196 of the second three-way valve 84. In each of these modesof operation, the second shutoff valve 100 is in the closed position andthe first shutoff valve 96 is in the open position. Upon exiting thesecond port 196 of the second three-way valve 84, the first heatexchange fluid is directed toward the first shutoff valve 96 by therefrigerant network of conduits 68. After flowing through the firstshutoff valve 96, the first heat exchange fluid encounters the firstcoupling point 200. At the first coupling point 200, first heat exchangefluid that exited the first three-way valve 72 by way of the third port268 is rejoined with the first heat exchange fluid that exited the firstthree-way valve 72 by way of the second port 176. Prior to reaching thefirst coupling point 200, the first heat exchange fluid that exited thefirst three-way valve 72 by way of the third port 268 passes through thefirst region 80 of the second heat exchanger 32. Within the second heatexchanger 32, the first heat exchange fluid thermally interacts with thesecond heat exchange fluid in the manner already described. From thefirst coupling point 200, the recombined first heat exchange fluid isdirected toward the first branching point 204. As the first heatexchange fluid encounters the first branching point 204, a portion ofthe first heat exchange fluid is diverted toward the first expansionvalve 116, while the remaining portion of the first heat exchange fluidcontinues toward the second region 112 of the vapor generator 48 in themanner already described. From the vapor generator 48, the first heatexchange fluid is directed toward the third shutoff valve 104.

Referring further to FIGS. 8 and 9 , from the third shutoff valve 104,the first heat exchange fluid is directed toward the third expansionvalve 124. The first heat exchange fluid experiences a decrease inpressure and temperature as a result of interaction with the thirdexpansion valve 124. After exiting the third expansion valve 124, thefirst heat exchange fluid is directed toward the inlet 224 of the thirdheat exchanger 36. The decreased temperature and pressure of the firstheat exchange fluid flowing through the third heat exchanger 36 can beemployed to provide cooling to air that is flowing through the ductwork154 with which the third heat exchanger 36 is in fluid communication.Accordingly, the first heat exchange fluid that exits the third heatexchanger 36 by way of the outlet 228 of the third heat exchanger 36 mayhave an increased pressure, temperature, and/or vapor percentage thanthe first heat exchange fluid that entered the third heat exchanger 36at the inlet 224. The cooling of the air within the ductwork 154 that isprovided by the third heat exchanger 36 in these modes of operation canbe employed as a way of controlling a humidity level within the aircirculated through the ductwork 154 (e.g., dehumidification). Uponexiting the third heat exchanger 36 by way of the outlet 228, the firstheat exchange fluid is directed toward the first port 232 of the thirdthree-way valve 88. As a result of the position of the third three-wayvalve 88, the first heat exchange fluid that is received at the firstport 232 is directed out of the second port 236 of the third three-wayvalve and toward the accumulator 92. The accumulator 92 receives thefirst heat exchange fluid and provides a gaseous components of the firstheat exchange fluid to the low-pressure inlet 56 of the compressor 44.

With specific reference to FIG. 9 , in addition to the third heatexchanger 36 receiving the first heat exchange fluid that exits thethird shutoff valve 104, the fourth heat exchanger 40 receives the firstheat exchange fluid that has exited the third shutoff valve 104. Morespecifically, in the fourth reheat mode of operation, the fourthexpansion valve 128 receives a portion of the first heat exchange fluidthat encounters the second branching point 240. As described above, atthe second branching point 240, the first portion of the first heatexchange fluid is directed toward the fourth expansion valve 128 and thesecond portion of the first heat exchange fluid is directed toward thethird expansion valve 124. As the interaction with the third expansionvalve 124 and the third heat exchanger 36 has already been discussedwith regard to the fourth reheat mode of operation, the interactionbetween the first portion of the first heat exchange fluid, the fourthexpansion valve 128, the fourth heat exchanger 40, and the check valve252 will now be focused on. The first portion of the first heat exchangefluid experiences a decrease in pressure and temperature as a result ofinteraction with the fourth expansion valve 128.

Referring again to FIG. 9 , after exiting the fourth expansion valve128, the first heat exchange fluid is directed toward the inlet 244 ofthe fourth heat exchanger 40. The decreased temperature and pressure ofthe first heat exchange fluid flowing through the fourth heat exchanger40 as a result of interaction with the fourth expansion valve 128 can beemployed to decrease the temperature of heat-producing components withwhich the fourth heat exchanger 40 interacts (e.g., electric motors,batteries, electronics, etc.). Accordingly, the first heat exchangefluid that exits the fourth heat exchanger 40 by way of the outlet 248of the fourth heat exchanger 40 may have an increased pressure,temperature, and/or vapor percentage than the first heat exchange fluidthat entered the fourth heat exchanger 40 at the inlet 244. Upon exitingthe fourth heat exchanger 40 by way of the outlet 248, the first heatexchange fluid is directed toward the check valve 252 by the refrigerantnetwork of conduits 68. Once the first heat exchange fluid passesthrough the check valve 252, the first portion of the first heatexchange fluid that was directed toward the fourth heat exchanger 40 isrejoined or recombined with the second portion of the first heatexchange fluid that was directed toward the third heat exchanger 36. Thefirst and second portions of the first heat exchange fluid are rejoinedor recombined downstream of the outlet 228 of the third heat exchanger36. The check valve 252 prevents backflow or excessive back pressure atthe outlet 248 of the fourth heat exchanger 40. From the check valve252, the first heat exchange fluid is directed toward the first port 232of the third three-way valve 88. As a result of the position of thethird three-way valve 88, the first heat exchange fluid that is receivedat the first port 232 is directed out of the second port 236 of thethird three-way valve and toward the accumulator 92. The accumulator 92receives the first heat exchange fluid and provides a gaseous componentsof the first heat exchange fluid to the low-pressure inlet 56 of thecompressor 44.

Referring now to FIGS. 10-12 , a first deicing mode of operation (FIG.10 ), a second deicing mode of operation (FIG. 11 ), and a heat anddeicing mode of operation (FIG. 12 ) are depicted in exemplary form. Ineach of these modes of operation, the compressor 44 drives the firstheat exchange fluid from the outlet 64 to the first port 172 of thefirst three-way valve 72. The positioning of the first three-way valve72 directs the first heat exchange fluid that is received at the firstport 172 to exit the first three-way valve 72 at the second port 176. Inthe heat and deicing mode of operation depicted in FIG. 12 , thepositioning of the first three-way valve 72 additionally directs thefirst heat exchange fluid that is received at the first port 172 to exitthe first three-way valve 72 at the third port 268. Accordingly, in theheat and deicing mode of operation depicted in FIG. 12 , the first heatexchange fluid flows into the first port 172 and out of both the secondport 176 and the third port 268. The first heat exchange fluid thatexits the second port 176 of the first three-way valve 72 is directedtoward the first port 156 of the four-way valve 52. Accordingly, thefirst port 156 operates as a first inlet, as indicated by arrow 320. Theposition of the four-way valve 52 directs the first heat exchange fluidreceived at the first port 156 to exit the four-way valve 52 at thefourth port 168 such that the fourth port 168 operates as a firstoutlet, as indicated by arrow 324. Upon exiting the fourth port 168 ofthe four-way valve 52, the first heat exchange fluid enters the firstheat exchanger 28 at the inlet 76 of the first heat exchanger 28. As thefirst heat exchange fluid flows through the first heat exchanger 28, thefirst heat exchange fluid may thermally interact with a heat exchangefluid that is external to the refrigerant loop 24 and the coolant loop132 (e.g., ambient air) such that heat may be removed from the firstheat exchange fluid.

With specific reference to FIG. 10 , the first heat exchange fluid exitsthe first heat exchanger 28 at the outlet 188 of the first heatexchanger 28. Upon exiting the first heat exchanger 28 by way of theoutlet 188, the first heat exchange fluid enters into the first port 192of the second three-way valve 84. The second three-way valve 84 ispositioned such that the first heat exchange fluid that is received atthe first port 192 is directed to exit the second three-way valve by wayof a third port 328 thereof. From the third port 328 of the secondthree-way valve 84, the first heat exchange fluid is directed toward acoupling point 332. From the second coupling point 332, the first heatexchange fluid progresses to the second expansion valve 120. The firstheat exchange fluid experiences a decreases in pressure and temperatureas a result of interaction with the second expansion valve 120. From thesecond expansion valve 120, the first heat exchange fluid is directtoward the third port 164 of the four-way valve 52. Accordingly, thepositioning of the four-way valve 52 in the first deicing mode ofoperation employs the third port 164 of the four-way valve 52 as asecond inlet, as indicated by arrow 336. As a result of the positioningof the four-way valve 52, the first heat exchange fluid that has enteredthe third port 164 is directed toward the second port 160 such that thesecond port 160 acts as a second outlet, as indicated by arrow 340. Fromthe fourth port 168 of the four-way valve 52, the first heat exchangefluid is directed toward the third port 308 of the third three-way valve88. The first heat exchange fluid received at the third port 208 isdirected to exit the third three-way valve 88 at the second port 236 asa result of the positioning of the third three-way valve 88. Theaccumulator 92 receives the first heat exchange fluid that exits thesecond port 236 of the third three-way valve 88 and provides a gaseouscomponent of the first heat exchange fluid to the low-pressure inlet 56of the compressor 44.

Referring to FIGS. 11 and 12 , the first heat exchange fluid exits thefirst heat exchanger 28 at the outlet 188 of the first heat exchanger28. Upon exiting the first heat exchanger 28 by way of the outlet 188,the first heat exchange fluid enters into the first port 192 of thesecond three-way valve 84. The second three-way valve 84 is positionedsuch that the first heat exchange fluid received at the first port 192is directed to the second port 196 of the second three-way valve 84. Ineach of these modes of operation, the second shutoff valve 100 is in theclosed position and the first shutoff valve 96 is in the open position.Upon exiting the second port 196 of the second three-way valve 84, thefirst heat exchange fluid is directed toward the first shutoff valve 96by the refrigerant network of conduits 68. After flowing through thefirst shutoff valve 96, the first heat exchange fluid encounters thefirst coupling point 200. With regard to FIG. 12 , at the first couplingpoint 200, the first heat exchange fluid that exited the first three-wayvalve 72 by way of the third port 268 is rejoined with the first heatexchange fluid that exited the first three-way valve 72 by way of thesecond port 176. Again with regard to FIG. 12 , prior to reaching thefirst coupling point 200, the first heat exchange fluid that exited thefirst three-way valve 72 by way of the third port 268 passes through thefirst region 80 of the second heat exchanger 32. With further referenceto FIG. 12 , within the second heat exchanger 32, the first heatexchange fluid thermally interacts with the second heat exchange fluidin the manner already described. From the first coupling point 200, thefirst heat exchange fluid is directed toward the first branching point204. As the first heat exchange fluid encounters the first branchingpoint 204, a portion of the first heat exchange fluid is diverted towardthe first expansion valve 116, while the remaining portion of the firstheat exchange fluid continues toward the second region 112 of the vaporgenerator 48 in the manner already described. From the vapor generator48, the first heat exchange fluid is directed toward the third shutoffvalve 104.

With specific reference to FIG. 11 , from the third shutoff valve 104,the first heat exchange fluid progresses to the second expansion valve120. The first heat exchange fluid experiences a decreases in pressureand temperature as a result of interaction with the second expansionvalve 120. From the second expansion valve 120, the first heat exchangefluid is direct toward the third port 164 of the four-way valve 52.Accordingly, the positioning of the four-way valve 52 in the seconddeicing mode of operation employs the third port 164 of the four-wayvalve 52 as a second inlet, as indicated by arrow 336. As a result ofthe positioning of the four-way valve 52, the first heat exchange fluidthat has entered the third port 164 is directed toward the second port160 such that the second port 160 acts as a second outlet, as indicatedby arrow 340. From the fourth port 168 of the four-way valve 52, thefirst heat exchange fluid is directed toward the third port 308 of thethird three-way valve 88. The first heat exchange fluid received at thethird port 208 is directed to exit the third three-way valve 88 at thesecond port 236 as a result of the positioning of the third three-wayvalve 88. The accumulator 92 receives the first heat exchange fluid thatexits the second port 236 of the third three-way valve 88 and provides agaseous component of the first heat exchange fluid to the low-pressureinlet 56 of the compressor 44.

With specific reference to FIG. 12 , from the third shutoff valve 104,the first heat exchange fluid is directed toward the fourth expansionvalve 128. The first heat exchange fluid experiences a decrease inpressure and temperature as a result of interaction with the fourthexpansion valve 128. After exiting the fourth expansion valve 128, thefirst heat exchange fluid is directed toward the inlet 244 of the fourthheat exchanger 40. The decreased temperature and pressure of the firstheat exchange fluid flowing through the fourth heat exchanger 40 as aresult of interaction with the fourth expansion valve 128 can beemployed to decrease the temperature of heat-producing components withwhich the fourth heat exchanger 40 interacts (e.g., electric motors,batteries, electronics, etc.). Accordingly, the first heat exchangefluid that exits the fourth heat exchanger 40 by way of the outlet 248of the fourth heat exchanger 40 may have an increased pressure,temperature, and/or vapor percentage than the first heat exchange fluidthat entered the fourth heat exchanger 40 at the inlet 244. Upon exitingthe fourth heat exchanger 40 by way of the outlet 248, the first heatexchange fluid is directed toward the check valve 252 by the refrigerantnetwork of conduits 68. From the check valve 252, the first heatexchange fluid is directed toward the first port 232 of the thirdthree-way valve 88. As a result of the position of the third three-wayvalve 88, the first heat exchange fluid that is received at the firstport 232 is directed out of the second port 236 of the third three-wayvalve and toward the accumulator 92. The accumulator 92 receives thefirst heat exchange fluid and provides a gaseous components of the firstheat exchange fluid to the low-pressure inlet 56 of the compressor 44.

As mentioned above, at least one component chosen from the first heatexchanger 28, the second heat exchanger 32, and the vapor generator 48is free from flow driven by the compressor 44 (i.e., compressor-drivenflow) of the first heat exchange fluid during a first predetermined setof heating modes of the heat pump 20 and a first predetermined set ofcooling modes of the heat pump 20. The first predetermined set ofcooling modes of operation of the heat pump 20 can include the coolingmode of operation (FIG. 2 ), the cabin and battery cooling mode ofoperation (FIG. 3 ), and/or the battery cooling mode of operation (FIG.4 ). The first predetermined set of heating modes of operation caninclude the first reheat mode of operation (FIG. 6 ), the second reheatmode of operation (FIG. 7 ), the first deicing mode of operation (FIG.10 ), and/or the second deicing mode of operation (FIG. 11 ).

Modifications of the disclosure will occur to those skilled in the artand to those who make or use the concepts disclosed herein. Therefore,it is understood that the embodiments shown in the drawings anddescribed above are merely for illustrative purposes and not intended tolimit the scope of the disclosure, which is defined by the followingclaims as interpreted according to the principles of patent law,including the doctrine of equivalents.

It will be understood by one having ordinary skill in the art thatconstruction of the described concepts, and other components, is notlimited to any specific material. Other exemplary embodiments of theconcepts disclosed herein may be formed from a wide variety ofmaterials, unless described otherwise herein.

For purposes of this disclosure, the term “coupled” (in all of itsforms: couple, coupling, coupled, etc.) generally means the joining oftwo components (electrical or mechanical) directly or indirectly to oneanother. Such joining may be stationary in nature or movable in nature.Such joining may be achieved with the two components (electrical ormechanical) and any additional intermediate members being integrallyformed as a single unitary body with one another or with the twocomponents. Such joining may be permanent in nature, or may be removableor releasable in nature, unless otherwise stated.

It is also important to note that the construction and arrangement ofthe elements of the disclosure, as shown in the exemplary embodiments,is illustrative only. Although only a few embodiments of the presentinnovations have been described in detail in this disclosure, thoseskilled in the art who review this disclosure will readily appreciatethat many modifications are possible (e.g., variations in sizes,dimensions, structures, shapes and proportions of the various elements,values of parameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter recited. For example,elements shown as integrally formed may be constructed of multipleparts, or elements shown as multiple parts may be integrally formed, theoperation of the interfaces may be reversed or otherwise varied, thelength or width of the structures and/or members or connector or otherelements of the system may be varied, and the nature or numeral ofadjustment positions provided between the elements may be varied. Itshould be noted that the elements and/or assemblies of the system may beconstructed from any of a wide variety of materials that providesufficient strength or durability, in any of a wide variety of colors,textures, and combinations. Accordingly, all such modifications areintended to be included within the scope of the present innovations.Other substitutions, modifications, changes, and omissions may be madein the design, operating conditions, and arrangement of the desired andother exemplary embodiments without departing from the spirit of thepresent innovations.

It will be understood that any described processes, or steps withindescribed processes, may be combined with other disclosed processes orsteps to form structures within the scope of the present disclosure. Theexemplary structures and processes disclosed herein are for illustrativepurposes and are not to be construed as limiting.

It is also to be understood that variations and modifications can bemade on the aforementioned structures and methods without departing fromthe concepts of the present disclosure, and further, it is to beunderstood that such concepts are intended to be covered by thefollowing claims, unless these claims, by their language, expresslystate otherwise.

What is claimed is:
 1. A heat pump, comprising: a refrigerant loopcomprising: a first heat exchanger; a first region of a second heatexchanger; a third heat exchanger; a fourth heat exchanger; a compressorhaving a low-pressure inlet, a mid-pressure inlet, and an outlet; avapor generator positioned downstream of the outlet of the compressorand upstream of both the low-pressure inlet and the mid-pressure inlet;and a four-way valve positioned immediately upstream of the first heatexchanger, wherein at least one component chosen from the first heatexchanger, the second heat exchanger, and the vapor generator is freefrom compressor-driven flow of the first heat exchange fluid during afirst predetermined set of heating modes of operation of the heat pumpand a first predetermined set of cooling modes of operation of the heatpump.
 2. The heat pump of claim 1, wherein the refrigerant loop furthercomprises: a first three-way valve positioned downstream of the outletof the compressor and upstream of an inlet of the first heat exchanger,wherein the first three-way valve is positioned upstream of the firstregion of the second heat exchanger.
 3. The heat pump of claim 2,wherein the four-way valve is positioned downstream of the firstthree-way valve.
 4. The heat pump of claim 3, wherein the refrigerantloop further comprises: a second three-way valve positioned immediatelydownstream of the first heat exchanger.
 5. The heat pump of claim 4,wherein the refrigerant loop further comprises: a third three-way valvepositioned downstream of the third heat exchanger, wherein the thirdthree-way valve is positioned downstream of the fourth heat exchanger,and wherein the third three-way valve is positioned upstream of thelow-pressure inlet.
 6. The heat pump of claim 5, wherein the refrigerantloop further comprises: an accumulator positioned immediately upstreamof the low-pressure inlet of the compressor and immediately downstreamof the third three-way valve.
 7. The heat pump of claim 1, wherein therefrigerant loop further comprises: a first shutoff valve plumbed inseries with the first heat exchanger; and a second shutoff valve plumbedin series with the first heat exchanger, wherein the first shutoff valveis in a closed position when the second shutoff valve is in an openposition, and wherein the second shutoff valve is in a closed positionwhen the first shutoff valve is in an open position.
 8. The heat pump ofclaim 7, wherein the refrigerant loop further comprises: a third shutoffvalve positioned downstream of the vapor generator.
 9. The heat pump ofclaim 1, wherein the vapor generator is a liquid-gas separator valve.10. The heat pump of claim 1, wherein the vapor generator is aplate-style heat exchanger.
 11. The heat pump of claim 10, wherein therefrigerant loop further comprises: a first expansion valve positionedupstream of a first region of the vapor generator.
 12. The heat pump ofclaim 11, wherein the refrigerant loop further comprises: a secondexpansion valve positioned upstream of the four-way valve; a thirdexpansion valve positioned immediately upstream of the third heatexchanger; and a fourth expansion valve positioned immediately upstreamof the fourth heat exchanger.
 13. The heat pump of claim 1, furthercomprising: a coolant loop comprising: a second region of the secondheat exchanger; a pump; a fifth heat exchanger; a reservoir; and acoolant network of conduits that fluidly couples components of thecoolant loop.
 14. A heat pump, comprising: a refrigerant loopcomprising: a refrigerant network of conduits that fluidly couplescomponents of the refrigerant loop; a first heat exchange fluidcirculating through the refrigerant network of conduits; a compressorhaving a low-pressure inlet, a mid-pressure inlet, and an outlet; afirst heat exchanger; a first region of a second heat exchanger; a thirdheat exchanger; a fourth heat exchanger; a vapor generator positioneddownstream of the outlet of the compressor and upstream of both thelow-pressure inlet and the mid-pressure inlet; a first three-way valvepositioned downstream of the outlet of the compressor and upstream of aninlet of the first heat exchanger, wherein the first three-way valve ispositioned upstream of the first region of the second heat exchanger;and a four-way valve positioned immediately upstream of the first heatexchanger, wherein at least one component chosen from the first heatexchanger, the second heat exchanger, and the vapor generator is freefrom compressor-driven flow of the first heat exchange fluid during afirst predetermined set of heating modes of operation of the heat pumpand a first predetermined set of cooling modes of operation of the heatpump.
 15. The heat pump of claim 14, wherein the refrigerant loopfurther comprises: a second three-way valve positioned immediatelydownstream of the first heat exchanger.
 16. The heat pump of claim 15,wherein the refrigerant loop further comprises: a third three-way valvepositioned downstream of the third heat exchanger, wherein the thirdthree-way valve is positioned downstream of the fourth heat exchanger,and wherein the third three-way valve is positioned upstream of thelow-pressure inlet.
 17. The heat pump of claim 14, wherein therefrigerant loop further comprises: a first shutoff valve plumbed inseries with the first heat exchanger; a second shutoff valve plumbed inseries with the first heat exchanger, wherein the first shutoff valve isin a closed position when the second shutoff valve is in an openposition, and wherein the second shutoff valve is in a closed positionwhen the first shutoff valve is in an open position; and a third shutoffvalve positioned downstream of the vapor generator.
 18. The heat pump ofclaim 14, wherein the refrigerant loop further comprises: a firstexpansion valve positioned upstream of a first region of the vaporgenerator; a second expansion valve positioned upstream of the four-wayvalve; a third expansion valve positioned immediately upstream of thethird heat exchanger; and a fourth expansion valve positionedimmediately upstream of the fourth heat exchanger.
 19. The heat pump ofclaim 14, wherein the refrigerant loop further comprises: an accumulatorpositioned immediately upstream of the low-pressure inlet of thecompressor and immediately downstream of the third three-way valve. 20.The heat pump of claim 14, further comprising: a coolant loopcomprising: a second region of the second heat exchanger; a pump; afifth heat exchanger; a reservoir; and a coolant network of conduitsthat fluidly couples components of the coolant loop.